Generally, a conventional semiconductor light-emitting device comprises a semiconductor light-emitting element mounted on a heat sink block which, in turn, is mounted on a stem. The semiconductor light-emitting element, the heat sink block and the stem are covered by a hollow envelope joined to the stem. Light goes out through a glass window provided in the hollow envelope. With this structure, the light-emitting element can be operated in a hermetically sealed, stable environment.
For stability against the environment, easy production, and reduced manufacturing cost of such semiconductor light-emitting devices, resin-molding is considered to be more advantageous. For example, as shown in FIG. 1, a semiconductor light-emitting element 1 is mounted on a base 4 with an Si submount 2 and a heat sink block 3 interposed therebetween, and the element 1, the submount 2 and the heat sink block 3 are sealed in a transparent resin on the base 4. Light 6 emitted from the semiconductor light-emitting element 1 emerges through the transparent resin 5.
Japanese Published Patent Application No. SHO 63-5579 discloses an optical connector module which comprises a semiconductor light-emitting element enclosed in a resin. The module includes a molded resin having a hollow cavity in which an optical semiconductor element is disposed. A cylindrical member for coupling the module to an optical fiber device protrudes from one surface of the resin. The resin in the vicinity of the semiconductor element has a high light reflectance so that the intensity of light coupled to the optical fiber is improved.
The emitted light 6 from the semiconductor light-emitting element 1 of the semiconductor light-emitting devuce shown in FIG. 1 is usually made to pass through one or more of optical elements, such as a beam splitter, a lens, an optical fiber, a glass plate and the like. The emitted light 6 must have an optically undistorted light intensity distribution so that coupling of light to an optical system is not adversely affected. If the light intensity distribution is distorted, it is difficult to, for example, properly thin a light beam. The emitted light 6 emerges from the device through a surface portion 7 of the transparent resin, and, therefore, the flatness of the surface portion 7 is critical. If the portion 7 does not have an optically desirable surface, the light intensity distribution of the emitted light 6 is distorted and, therefore, undesired optical coupling with a succeeding optical system may result. In order to provide an optically desirable surface for the portion 7, the portion 7 could be finished by, for example, polishing. However, it is difficult to aschieve a flatness of the same degree as optical elements on the surface portion 7, and the yield is poor. Furthermore, since ordinary resins are easily damaged and poor in etch-resistance, the surface of such resins is not suitable for use as a light emerging surface.
The previously mentioned Japanese Published Application No. SHO 63-5579 discloses enclosing a semiconductor light-emitting element with a resin, but it is not intended to overcome the above-discussed problems.
According to the present invention, a semiconductor light-emitting device is provided, in which a semiconductor light-emitting element is sealed in a transparent resin and which can provide a stable light output with an undistorted intensity distribution.